<div id="sphere"></div>

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  width: 100%;
  height: 100vh;
  background: rgb(29, 28, 31);
}

#sphere {
  width: 300px;
  height: 300px;
  position: absolute;
  top: calc(50% - 150px);
  left: calc(50% - 150px);
  border-radius: 50%;
  background: radial-gradient(200px circle at 20% 30%, rgb(144, 206, 233) 0%, rgb(104, 114, 155) 35%, rgba(52, 25, 28, 0.4) 97%, rgba(31, 25, 28, 1) 100%);
}

/**
 * Old css snippet - missing original image.
 * If anyone knows the author, please let me know to give the credit.
 */